Abstract 502: Glucose-6-Phosphate Dehydrogenase Regulates MYH11 and MYOCD Expression in HDAC and miR-1 Dependent Manner

Abstract

Vascular smooth muscle cell (VSMC) phenotype and function is altered in diabetic and obese patients and animals. Increased activity of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in Pentose Phosphate Pathway, in diabetic and obese animals is associated with decreased expression of MYOCD and MYOCD-dependent genes in the arteries of these animals. Therefore, we hypothesize that reprogrammed metabolism and increased G6PD activity is critical in switching the VSMC from a differentiated to a dedifferentiated phenotype. Our results demonstrated metabolic reprogramming and decrease in MYOCD and MYOCD-driven MYH11 in the aorta of normal chow- and high fat diet (HFD)-fed diabetic Goto-Kakizaki (GK) as compared to control rats. Up regulated G6PD activity in the aorta of these animals positively correlated with increased arterial elastance (R 2 = 0.8322) and total peripheral resistance (R 2 = 0.8364). In vitro , VSMCs (A7r5) treated with Ad-shRNA for G6PD, epiandrosterone (Epi), G6PD inhibitor, and PD2958, a selective inhibitor of G6PD activity, increased (P<0.05) Myocd and Myh11 levels and MYOCD-regulated MYH11 and CNN1 expressions as compared to untreated cells. Furthermore, we found that G6PD-mediated expression of MYOCD and MYH11 expressions was regulated at transcriptional and post transcriptional level. Inhibition of G6PD by PD2958 or Epi decreased histone deacetylase (HDAC) activity by 70-80% (P<0.05), and concomitantly, PD2958 and Ad-shRNA-G6PD up regulated H3K9Ac expression in A7r5 cells as compared to their respective controls. Next, we compared the expression of VSMC-restricted MYH11 in A7r5 cells treated with HDAC inhibitor, Trichostatin (TSA), and PD2958+TSA. Our results demonstrated that MYH11 expression increased by TSA and PD2958 was not further potentiated by PD2958+TSA, suggesting that G6PD inhibition up regulated MYH11 via HDAC inhibition. We also found that G6PD inhibition increased miR-1 levels, which post-transcriptionally regulates MYOCD and MYOCD-dependent gene expression. Therefore, our results collectively suggest that increased G6PD activity is associated with switching of VSMCs from a differentiated to a dedifferentiated phenotype in HDAC and miR-1 dependent manner.